The Lake Simcoe Region Conservation Authority

Riverine Flood Status
Lake Simcoe Shoreline Status
Low Water Status

Water Quality

Water Quality in our Rivers and Streams

​In the Lake Simcoe watershed, the greatest impacts to water quality will be in changes to phosphorus, chloride, and total suspended solids.


Although phosphorus is an essential nutrient for plants, at high concentrations it encourages excessive plant growth, which in turn decreases oxygen levels and disrupts ecosystems. The total amount of phosphorus (phosphorus load) flowing into Lake Simcoe comes from several sources but is generally highest in the most urbanized subwatersheds. As extreme rain events become more frequent, they will lead to increased phosphorus loading, perhaps dominated by large “pulse” events.


Chloride is a naturally occurring element essential for the health of all organisms, but too much chloride has a negative impact on our aquatic ecosystems. Most chloride in the watershed comes from winter road salt application, which has resulted in concentrations being above the chronic guidelines, established by the Canadian government, in urban catchments or near major highways. With varying winter temperatures and more freeze-thaw cycles, our need for road salt increases, leading to increased concentrations of chloride.

Total Suspended Solids

Total suspended solids (TSS) includes things like silt, sand, microorganisms, plant or animal matter, and industrial wastes that remain suspended in the water column. Excessive amounts of TSS can negatively impact streams and rivers as it can transport phosphorus, decrease light penetration, and alter aquatic habitats. Most monitoring stations in our watershed have shown concentrations exceeding the Canadian guidelines during low water or storm conditions. As rain events have become more intense, urban subwatersheds have been particularly at risk for increased TSS which can transport contaminants into aquatic ecosystems.​

phone icon   Who to Contact 


Integrated Watershed Management 
1-800-465-0437 Toll free

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